The objectives of the proposed work are: 1.) to elucidate the organization of mammalian cerebellar pathways (both intrinsic and extrinsic) by means of their experimental degeneration in animals, using a selective reduced silver method at the light microscopic level and the electron microscope, 2.) to apply the same selective silver methodology in studies of human central nervous system degeneration, as presented in appropriate postmortem material, and 3.) to continue to investigate the mechanisms involved in the selective staining of neuronal degeneration by reduced silver methods, especially with respect to how these mechanisms reflect specific morphological and biochemical changes in the degeneration of neuronal structures.